The overall objectives of our program project are to effectively integrate and focus the collective expertise of participating investigators in studies designed to define and elucidate the immunopathologic mechanisms responsible for diseases associated with asthma, IgE mediated allergy, and/or urticaria. During the current year we propose: 1) studies of the mediators (histamine, complement system, contact system, and prostaglandins) in experimentally provoked (aspirin, exercise, cold, or allergen inhalation) asthma; 2) studies of the mediators in hypocomplementemic patients with chronic urticaria or systemic lupus erythematosus; 3) studies of the effect(s) of Cl inhibitor deficiency on the activation of complement and contact systems in patients with hereditary angioedema; and 4) studies of the role(s) of IgE synthesis in the pathogenesis of allergy in allergic individuals.